1. Field of the Invention
This invention relates to a pipe coupling for the union of corrugated pipes.
2. Description of the invention
Heretofore, as a means for the union of corrugated pipes, a pipe coupling which comprises a pipe coupling proper and a lock cylinder adapted to be helically joined to the inner surface of the leading part of the pipe coupling proper and provided with lock means capable of attaching fast thereto a corrugated pipe inserted therein and which, therefore, enables the corrugated pipe to be fixed and, at the same time, pushed in the same direction until the leading terminal part thereof is pressed against a seal ring inside the pipe coupling proper to seal the pipe coupling proper by closing the lock cylinder helically tacked to the pipe coupling proper has been known in the art.
Another pipe coupling has been known in the art which comprises a pipe coupling proper provided on a leading terminal side thereof with a large-diameter through hole. In a recessed part thereof is a small-diameter through hole. In a connecting stepped part joins the large-diameter through hole and the small-diameter through hole with a circumferential groove and a stopper part for securing the leading part of a corrugated pipe. The circumferential groove has a seal ring for insertion therein and a lock cylinder provided with an annular groove part adapted for helical union with the inner surface of the large-diameter through hole of the pipe coupling proper and possessed of a through hole roughly equal in diameter to the outside diameter of a corrugated pipe and a tapered surface on the rear terminal side inner wall of the through hole and a circumferentially expansible rigid ring inserted in the circumferential groove part. This therefore enables the rigid ring to be depressed by the circumferential groove part of the lock cylinder into fast engagement with the outside-diameter groove of the corrugated pipe inserted in the pipe coupling and consequently causes the corrugated pipe to be pushed in the same direction until the leading terminal part thereof is brought into engagement with the stopper part of the pipe coupling proper and pressed in a plastically deformed state into contact with the seal ring by rotationally closing the lock cylinder helically tacked to the pipe coupling proper.